Hengel family via APThis undated photo provided by the Hengel family shows Sam Hengel, who authorities say shot himself Monday night Nov. 29, 2010 when police stormed the Marinette High School classroom in Marinette Wis., where he'd held about two dozen other students and teacher. No others were injured.

It has been three days since a 15-year-old Wisconsin student took his high school hostage for six hours before killing himself, and police and his classmates still don't understand why.

Sam Hengel was a good student with a lot of friends who wasn't bullied. He didn't explain himself during the standoff, and he never threatened or pointed his gun at anyone. He even chatted with his captives about hunting.

Hengel didn't leave any notes, and police are still combing through social networks such as Facebook for answers.